Power supplies in electronic systems, such as automobile electrical systems, are subject to potential damage if a short-circuit or an excess current condition occurs. Present technology protects system power supplies by using active current sensors to determine if excess current is drawn from the power supply. Other existing technology involves the use of heat sensing devices to determine if the load device in the system or the pass transistor in the power supply is conducting excessive heat. If excess current or excess heat is detected in the system, the electrical system is shut down prior to the power supply incurring any damage. However, the use of active current sensors and heat sensing devices is not as cost effective as using individual electronic components. Moreover, the use of active current sensors and heat sensing devices requires complex methodologies to compensate for general temperature variations which are not as efficient as the present invention. Accordingly, there exists a need for an electronic control circuit that protects the system power supply from short-circuit or excess current conditions without requiring the use of an active current sensing device or heat sensing device.